Device for positioning in a volume

ABSTRACT

The invention relates to a device for heat exchange and positioning in a volume, the device comprising: a central body containing a material for storing thermal energy by latent heat accumulation, to be placed in thermal exchange with a circulating surrounding fluid, and a structure for positioning the central body in the volume, the positioning structure being connected to the central body around which it extends and reserving passages enabling contact between the central body and the surrounding fluid and the circulation of said fluid.

The present invention relates to the field of thermal management. In particular, it relates to a thermal management system for the circulation and heat exchange with a fluid.

In a volume, a fluid circulating therein may, at a certain time, carry thermal energy which, if stored then, can be returned later, in this volume, for example to the same fluid which may then have to circulate at another temperature, and therefore be able to benefit from this (at least partial) return of thermal energy.

For example, in a motor vehicle, the engine oil is very hot when the propelling engine has been running for some time. It may then be useful to store some of this thermal energy. On the other hand, when cold-starting the engine, heating the engine oil would be useful for engine performance and for limiting pollutant emissions.

In addition to the way in which thermal energy is stored and then released, a problem also rises for ensuring this function as well as possible while finding a compromise between a flow of the fluid in the volume concerned and the residence time/performance ratio of heat exchanges in the volume.

Therefore, a thermal management system is proposed that includes:

-   -   a housing having a hollow interior, an inlet and an outlet for a         fluid and, disposed in said hollow interior:     -   a plurality of heat exchange and positioning devices each         comprising:         -   a central body containing a material for storing thermal             energy by latent heat accumulation, to be placed in thermal             exchange with the fluid, and         -   a structure for positioning the central body in said hollow             interior, the positioning structure being connected to the             central body around which it extends and reserving passages             enabling contact between the central body and the             surrounding fluid and a circulation of said fluid. Thus, in             this case, an adapted flow of the fluid and a relative             positioning of the devices will be associated in order to             ensure important thermal exchanges.

To effectively position the central body while taking into account possible surrounding shapes and/or a possible need to orient the fluid locally by channelling it locally, it is proposed that the positioning structure should include an external structure:

-   -   (substantially or globally) defining a cylinder,     -   and connected by transverse arms to the central body.

In some cases, a positioning structure comprising an external structure defining a ring and connected by transverse arms to the central body will be sufficient.

An advantage will be to be able to reduce the interval between two central bodies of two adjacent devices since the positioning structure will then only extend (substantially) in one plane. Outside this plane, two adjacent devices may follow each other and be in contact.

And in order to take into account the difficulties of installation, storage or maintenance, a system comprising several devices connected together in a string by a flexible link, and in particular with a succession of external structures each defining a ring, can be proposed.

For a self-positioning that can be omnidirectional, regardless of the shape of the volume defined by said hollow interior, and a surrounding fluid flow that is also independent of the position of the device in this volume, it is proposed that the positioning structure should include a peripheral structure extending circumferentially around the central body, in several planes, to separate it from a surrounding support in several directions.

In particular, the positioning structure may then include an external structure:

-   -   defining a discontinuous sphere (with fluid passage and         circulation openings),     -   and connected by transverse arms to the central body.

If the positioning structure with a diameter of about 2 cm is connected to a central body with a diameter of about 1 cm by about fifteen straight rods having a cross-section of filamentary dimension (therefore of the order of 1 mm) and if the discontinuous sphere also consists of rectilinear but curved rods, it will be possible to combine strength, energy performance and respect for a circulation without excess pressure drop.

Preferably, the central body will be in the form of a sphere or of a profile. The sphere is omnidirectional.

In the above embodiments with external structures, the latter will a priori be radially distant from the central body. This is typically favourable in a duct where the transverse arms will only provide a radial mechanical connection to the central body with little resistance to fluid flow.

In a storage volume such as a storage exchanger balloon, where there are no tubular shapes as in a duct, it has been understood from the above that the problem may be rather to have said devices distant from each other and from the external wall, just enough not to prevent almost any circulation of the fluid, but giving priority to the number of devices per cm2, in order to obtain a maximum heat exchange.

Preferably, each central body can also be in the form of a sphere, to be easily used and distributed, with a minimum of dead space.

As for the positioning structure, it can include the following, while surrounding the central body, in contact therewith:

-   -   a honeycomb structure,     -   or one or more linear beads surrounding the central body,     -   or recesses formed in the external surface of said body.

In this way, on the one hand, the exchange surface between the body and the surrounding fluid coming into contact with it will be increased, and on the other hand, the passage of this fluid will be promoted, depending on the case between the beads or in the cells, or in said recesses, which will then define natural fluid passage channels.

The device produced will advantageously be a single-piece moulding integrating the positioning structure and the central body containing the thermal energy storage material.

And this material will advantageously include at least one PCM (phase change material) enabling high energy performance.

For all purposes, it is furthermore confirmed that a phase-change material—or PCM—refers to a material capable of changing physical state, between solid and liquid, within a restricted temperature range of between −50° C. and 180° C. The heat transfer (or thermal transfer) can be achieved by using the Latent Heat (LH) thereof: the material can then store or transfer energy by changing state, while keeping a substantially constant temperature, that of the change of state.

The thermally insulating material(s) associated with the PCM(s) may be a “simple” insulator such as glass wool, but a foam, for example of polyurethane or polyisocyanurate, or even more favourably a porous or even nano-porous thermally insulating material such as an aerogel, will certainly be preferred.

BRIEF DESCRIPTION OF THE DRAWINGS

If necessary, the invention will be better understood and other characteristics, details and advantages thereof will become apparent upon reading the following description as a non-exhaustive example with reference to the appended drawings in which:

FIGS. 1,2,3 schematize the first three examples, where a positioning structure ensures an axial centering of a central body in a volume,

FIGS. 4.5 schematize a set of devices according to for example FIG. 3, positioned in a volume in the form of a receptacle (especially in FIG. 4, only some of said heat exchange and positioning devices have been represented and the sinuosities followed by the flow that said devices prevent from flowing substantially axially, as in a duct or tube are visible; the residence time is thus increased as compared to a positioning in a duct), and

FIGS. 6, 7, 8 show three other examples (in cross-section and volume) where a positioning structure provides a spacing enabling the fluid flow between the devices illustrated positioned in a volume.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Several configurations of device 1 for heat exchange and positioning in a volume also called hollow interior, 3 or 21 of a receptacle can therefore be imagined.

Systematically, the device 1 will include:

-   -   a central body 5 containing a material 7 for storing thermal         energy by latent heat accumulation, to be placed in thermal         exchange with a circulating surrounding fluid 9, and     -   a structure 11 for positioning the central body in said volume,         the positioning structure 11 being connected to the central body         5, around which it therefore extends, and reserving passages 13         enabling fluid contact between the central body 5 and the         surrounding fluid 9, with a maintained circulation of said         fluid.

On the first three preferred examples below, the positioning structure 11 can ensure an axial centering of the central body 5 in the volume, when the positioning is in a duct 15, therefore in a tubular means, but a bulk positioning as FIGS. 4.5 is also possible. The positioning structure 11 will reserve passages 13 between same and the central body 5.

In the first example, as shown in FIG. 1, the positioning structure 11 includes an external structure 17 (substantially or globally) defining a cylinder and connected by transverse arms 19 to the central body 5.

With this hollow external structure 17 and fine arms, an axial self-centering (axis 15 a) is provided.

As in the following embodiments, the body 5 is here in the form of a sphere. But it can be shaped like a shell, to further limit pressure drops, with a volume reserved for material 7 which can remain the same.

The cylinder 17 may not be solid, but consist of branches or lines defining such a cylindrical envelope, but with passages through it to lighten same.

In the second example, as shown in FIG. 2, the positioning structure 11 includes an external structure 170 defining a ring and connected back to the central body 5 by transverse, or radial, arms 19.

In the third example, as shown in FIG. 3, the positioning structure 11 includes a peripheral, radially external structure, 270 defining a discontinuous sphere and connected by transverse or radial arms 190 to the central body 5 containing the material 7. The sphere is discontinuous in that it has openings 271 which pass through its spherical surface, so that the fluid 9 to be circulated passes through these openings, and thus reaches the central body 5. The openings 271 belong to the passages 13. As in other solutions presented here and for example illustrated in FIGS. 6-8, the solution of FIG. 3, with its transverse arms 190 and peripheral structure 270 with discontinuous spherical surface, makes it possible to achieve a positioning structure 11 extending circumferentially around the central body, in several directions and planes, and therefore not only according to a single diameter as is the case in the ring solution 170 in FIG. 2, where the ring spreads the body 5 on a single circumference, following the diametral plane in which the ring 170 extends. Such multidirectional self-positioning can also be achieved with the solutions of FIGS. 6-8.

The first and third examples are self-centering solutions in a duct, or even in a volume 3 which would be formed by the hollow interior 21 of a box 23, as in the example in FIGS. 4, 5 where a part of such a storage exchanger box having an inlet and an outlet for the fluid 9 and containing here several devices 1 in conformity with those of the third example is shown. A fluid 9 arriving in this volume will exchange, if the temperature is appropriate, with the thermal energy storage material 7 of the bodies 5, then continue its path as shown by the arrows.

The respective fluid inlets 22 a and outlets 22 b in the hollow interior 21 will advantageously form collars with respect to the hollow interior 21 (see FIG. 4), unlike a duct where the cross-sections are similar between the inlet/inner section/outlet. In all the exemplary embodiments mentioned in this description, the material 7 may consist of at least one PCM.

It may particularly be PCMs encapsulated (typically microencapsulated) in a porous matrix, with open pores, preferably of the elastomer type, such as a silicone-, NBR- or HNBR-based one. For each body 5, a rubber composition as described in EP2690137 or EP2690141 may be used.

The material 7 may also be based on paraffin, eutectic (myristic-capric) fatty acid or eutectic hydrated salt (calcium chloride+potassium). Other possibilities still exist for each body 5, such as a PCM impregnated in a porous network.

It should however be noted that any PCM may have a change of phase or state at a predetermined temperature peak or which is established over a more or less wide temperature range. Thus, with a pure PCM (such as a paraffin) the state change temperature will be constant, whereas it may be non-constant with several PCMs, such as for a mixture of paraffins.

To place or remove a series of many devices 1, it is proposed to connect together these devices 1 positioned in a line or a string, as shown in FIG. 2, using a flexible link 27 enabling at least some of the rings 170 to be oriented from outside the duct 15 so as to bring them closer to a position where these rings are in a plane radial to the local axis 15 a of the duct.

The flexible link 27 may include three filamentary strands passing through three openings (such as the one marked 29), provided each in one arm 19, near the ring 170 considered.

An overlength of the filamentary strands could make it possible to operate same from a distance, once the string has been slipped into its receptacle 3/21.

In the embodiment of the system 30 for the circulation and heat exchange with the fluid 9 illustrated in FIG. 4, it should also be noted that the solid wall 31 which delimits the volume 31/21 is surrounded by a thermal insulator 33 which will promote thermal management at the location of this duct, with the devices 1 placed inside. In the example of FIG. 5, a part of a storage and exchanger box 23 is shown, thus presenting the respective inlets and outlets 22 a, 22 b mentioned above, for the fluid 9, and containing here several devices 1 which can be in conformity with those of the third example (FIG. 3). A fluid 9 arriving in this volume will therefore exchange, if the temperature is appropriate, with the thermal energy storage material 7 of the bodies 5, then continue its path as shown by the arrows. Each positioning structure 11 is in the form of a peripheral structure extending circumferentially around the central body 5, in several planes, to spread this body in several directions from a surrounding support defined here by the walls 210 limiting the recess 21.

Three other examples are schematized in FIGS. 6, 7, 8 in particular turned towards the placing of devices 1 in such a hollow interior 21, or receptacle, for example that of a housing.

In the example shown in FIG. 6, the positioning structure 11 of each device 1 is in the form of several beads 35 surrounding the central body 5 containing the material 7 for storing thermal energy by latent heat accumulation.

The beads 35 can define at least two intersecting strips so as to maintain a free space 37 between several devices 1, each having a spherical shape here, so that, when placed in the hollow interior 21, these shapes 1 accumulate in the highest possible number, without loss of space, while enabling the fluid 9 to flow with a heat exchange between them.

The same comment can be applied to the second and third examples in FIGS. 7, 8 where, respectively, the positioning structure 11 is in the form of:

-   -   recesses 39 formed in said body 5,     -   and a honeycomb structure 41 surrounding the central body 5,         when in contact therewith.

The free spaces 37 between the devices 1 placed in the hollow interior 21 will still exist, each having a general spherical shape.

The recesses 39 will form blind cavities, for example each as a portion of a sphere.

In both cases, the central body 5 will extend at the bottom of said recesses and cells, or even between them.

The honeycomb structure 41 will also be open to the outside.

For producing any of these structures, it may be preferable to use a single-piece casting between the positioning structure 11 and the body 5. With reference to the above, the central body 5 could therefore be a porous matrix, with open pores, for example of the elastomer type.

In terms of heat exchange coefficient with comparable diameters, the solution in FIG. 8 is the most efficient one, followed by FIG. 7 and FIG. 6.

It should be noted that FIG. 7 also schematises in dotted lines an alternative solution to the recesses 39, namely orifices 40 going through the body 5, the lips 40 a of these orifices which lead to the outside (and which extend around the central body, locally) having little risk of being blocked by a solid wall part of another, here spherical device 1. The orifices 40 will define the above passages through which the surrounding fluid passes.

In the case of FIG. 6, the circumferential beads 35 disposed in different planes ensure the multi-directional spacing of the body 5. In the examples of FIGS. 7,8, the here spherical wall 390, between the recesses 39, and the walls 410 that limit and separate the cells 41 respectively play this part. 

1. A thermal management system including: a housing having a hollow interior, an inlet and an outlet for a fluid, and, disposed in said hollow interior: a plurality of heat exchange and positioning devices (1), each comprising: a central body containing a material for storing thermal energy by latent heat accumulation, to be placed in thermal exchange with the fluid, and a structure for positioning the central body in said hollow interior, the positioning structure being connected to the central body around which it extends and reserving passages enabling contact between the central body and the surrounding fluid and a circulation of said fluid, wherein: the positioning structure comprises an external structure defining a cylinder and connected by transverse arms to the central body, or the positioning structure comprises an external structure defining a ring and connected by transverse arms to the central body, or the positioning structure includes a peripheral structure extending circumferentially around the central body, in several planes, to separate it from a surrounding support in several directions, or the positioning structure includes an external structure: defining a discontinuous sphere, and connected to the central body by transverse arms around the central body, or the positioning structure is in the form of a cellular structure surrounding the central body, in contact with it, or the positioning structure includes one or more linear beads surrounding the central body, in contact with it, or recesses formed in said body.
 2. A system according to claim 1, wherein the thermal energy storage material of the central body comprises at least one PCM.
 3. A system according to claim 1, which is a one-piece casting between the positioning structure and the central body which contains the thermal energy storage material.
 4. A system according to claim 1, wherein several of said devices are connected together in a string by a flexible link.
 5. A system according to claim 1, wherein two said adjacent devices in said hollow interior are in contact with each other. 6-11. (canceled) 